In the field of office maintenance, and in other settings and environments, it is a common practice to replace locks used for drawers and/or doors as a security measure. Such replacements and/or changes may be part of an ongoing, periodic security maintenance plan, and/or the changes may be a result of more ad hoc circumstances, for example, accompanying a change in authorized personnel. Improving the security functionality of the associated locks would be one way to address such security needs. Another way to address such security needs could involve use of so-called removable core locks, for literally changing out the core lock functionality such that an entirely different key becomes operable with the lock. The present subject matter addresses both such approaches to lock security maintenance improvement.
Normally, changing or replacing locks can take extended periods of time unless removable core locks are employed. In general, the basic concept of providing removable core locks has been available for a period of time, and the use of such locks in general may significantly reduce (literally from hours to minutes) the time required to change locks for which re-keying is desired. However, embodiments of previously known removable core locks are often mechanically complex. In general, the more mechanically complex a device, the higher its cost, the larger its size, and the more questionable its reliability may tend to be. In view of such general disadvantages of many previously available removable core locks, it would be an advance in the art to provide a lock and associated methodology which resulted with a reduced part count that also required less precision to align the parts during assembly.
Another potential vulnerability of some key operated pin tumbler lock designs involves an unauthorized practice where there is unintentional activation of the tumbler by a key. For example, in some situations, it may be possible for an unauthorized person to use a modified key partially inserted and then manipulated or “bumped” in a particular manner, as an effort to cause spring-biased tumblers to very temporarily be displaced to an extent that either the lock itself or some removable core portion of a removable core lock may be actuated, thus permitting access by an unauthorized person. It would be an advance in the art to provide a key operated pin tumbler lock and associated methodology which was less potentially susceptible to such unintentional activation of the tumbler by a key by unauthorized persons.
Existing patent literature has previously addressed various pin tumbler lock arrangements and various removable core lock arrangements for pin tumbler locks. Some examples of issued patents include U.S. Pat. No. 6,679,090; U.S. Pat. No. 6,578,396; U.S. Pat. No. 6,526,791; U.S. Pat. No. 6,382,006; U.S. Pat. No. 6,012,311; U.S. Pat. No. 5,979,200; U.S. Pat. No. 5,907,963; U.S. Pat. No. 5,209,087; U.S. Pat. No. 5,176,015; U.S. Pat. No. 5,138,856; U.S. Pat. No. 5,070,715; U.S. Pat. No. 4,972,695; U.S. Pat. No. 4,866,964; U.S. Pat. No. 4,584,855; U.S. Pat. No. 4,444,029; U.S. Pat. No. 4,424,693; U.S. Pat. No. 4,386,510; U.S. Pat. No. 4,328,690; U.S. Pat. No. 4,282,731; U.S. Pat. No. 4,085,601; U.S. Pat. No. 3,603,123; U.S. Pat. No. 3,324,693; U.S. Pat. No. 3,206,958; and U.S. Pat. No. 2,814,941. The disclosures of all the foregoing published patents are for all purposes fully incorporated herein by reference.
While various implementations of key operated pin tumbler locks and related methodology, both involving and not involving removable core locks, have been developed, no design has emerged that generally encompasses all of the desired characteristics as hereafter presented in accordance with the present subject matter.